1. Field of the Invention
The present invention relates to a gate circuit connected to the gate of a power device.
2. Background Art
Japanese Laid-Open Patent Publication No. 2002-353795 discloses a gate circuit connected to the gate of a power device. When an excessive current flows through the power device, this gate circuit functions so that part of the gate supply voltage appears across a resistive element. This serves to reduce the voltage actually applied to the gate of the power device, thereby reducing the excessive current in the device.
In order to quickly reduce the excessive current in the power device, it is desirable to reduce the resistance value of the above resistive element. It should be noted that the power device is turned off after reducing the excessive current. In the gate circuit disclosed in the above patent publication, however, the power device is turned off by use of a resistive element of a relatively low resistance value connected to its gate. This results in a rapid rate of decrease in the current (di/dt) in the power device, which has been found to cause a surge voltage in some cases.